Relationship between the South China Sea summer monsoon and the first-landfall tropical cyclone over mainland of China

This study investigates the relationship between the South China Sea summer monsoon and the first tropical cyclone (TC) of the season to make landfall over mainland China (in short, the first-landfall TC) using the South China Sea summer monsoon index, NCEP/NCAR reanalysis monthly average data, and best-track TC data from Joint Typhoon Warning Center (JTWC) for 1948-2009. The results show that the characteristics of the first-landfall TC are closely associated with the frequency, active stage, and strength of subsequent landfall TCs in the same year. In detail, a stronger (weaker) South China Sea summer monsoon index year corresponds to more (fewer) landfall TCs over Mainland China, a later (earlier) date of the first-landfall TC, a lower (higher)-latitude landing point of the first-landfall TC, and a stronger (weaker) monsoon trough. The anomalous wind field and the track of the first-landfall TC are also significantly related to the strength of the index. The location of the first-landfall TC has shows a gradual trend toward higher latitudes over the analysis period, and there is a decreasing trend in the variability of the South China Sea summer monsoon index.